Electrical submersible well pumps (“ESP”) are commonly used to produce well fluid from hydrocarbon producing wells. A conventional ESP has a pump operatively coupled to an electrical motor for driving the pump. A pressure equalizer or seal section is normally located between the motor and the pump, but it could also be located at a lower end of the motor. A shaft seal below the pump intake seals the drive shaft extending from the motor. Shaft seals are typically mechanical face seals, thus over time tend to allow a small amount of well fluid to leak into communication with the motor lubricant. The well fluid usually contains water, thus can be damaging to the motor.
In some instances, ESPs are installed in horizontal sections of a well. A labyrinth disc chamber may be employed to further inhibit encroachment of well fluid into contact with the motor lubricant. The labyrinth chamber is made up of a number of discs stacked against one another. The discs are configured to define cavities between them. Each disc has a disc port that allows fluid to flow from one cavity to the next. The disc ports of the discs are arranged at different angular locations relative to the axis so as to require any well fluid to migrate upward and downward along a tortuous flow path. Each disc has a central aperture with a seal that seals against the shaft to require well fluid within the cavities to flow through the disc ports.